The worst is when you're actually in the middle of a boss fight in an end-game instance. The player obviously does not know what the zone name refers to and therefore likely is not a very hardcore/skilled player.

-Heart

At the brink of danger I stand. Clad in armour, shield and sword in hand.

Try being a leet hunter... everytime I step foot in Nagrand I get whispers asking to help kill the four elites or Durn and everytime I'm farming plants in Hellfire a level 62 asks me to help him kill the Fel Rever. I don't want to kill the Fel Rever!!! And if I did I wouldn't be doing it with a level 62 rogue!!!

And when you're 70 every level lower than you assumes your pet can tank whatever it is they want to kill and that you don't need a healer because you have mend pet.